Transfer roller assembly

ABSTRACT

A transfer roller assembly including a transfer roller and a rotary cleaning brush for an electrostatographic machine. The transfer roller assembly is rotated about a support shaft and in pressure contact with the photoconductive surface during the image transfer mode therefor. The transfer roller assembly includes a rotating cleaning brush in cleaning contact with the transfer roller and is movable with the roller about the support shaft. Separate drive mechanisms from a single drive member on the assembly provide independent rotation to the roller and the brush.

[ Nov. 12, 1974 1. No. 3. Oct

1 l l l OTHER PUBLICATIONS D. J. Oldenboom, Electromechanical TransferMechanism", IBM Tech. Disclosure, Vol. 1958.

Primary Examiner- W. C. Reynolds Assistant E.\'aminerLeo Millstein [57]ABSTRACT A transfer roller assembly including a transfer roller andarotary cleaning brush for an electrostatographic machine. The transferroller assembly is rotated abouta support shaft and in pressure contactwith the photoconductive surface during the image transfer modetherefor. The transfer roller assembly includes a rotating cleaningbrush in cleaning contact with the transfer roller and is movable withthe roller about the support shaft. Separate drive mechanisms from asingle drive member on the assembly provide independent rotation to theroller and the brush.

2 Claims, 7 Drawing Figures TRANSFER ROLLER ASSEMBLY Inventors: DanielS. Hoffman; Gilbert E. Koch, both of Rochester, NY. Assignee: XeroriCorporation, Stamford,

Conn.

Filed: Mar. 27, 1972 Appl. No.: 238,045

118/637, 118/262, 355/3 Int. Field of Search 118/261, 203, 204, 70;355/3, 12, 15; 96/l.4

References Cited UNITED STATES PATENTS 11/1958 Hix et al. 10/1963Bickmore et al. 7/l97l Kaupp................. 2/1972 Egnaczak........691,993 9/1972 Krause............ 724,422 4/1973 Latone et United StatesPatent Hoffman et al.

sum for 4 PAIENTED ROY l2 IHi-G PAIENIEDNuv 12 I974 sum 20$ 4 3847319 lTRANSFER ROLLER ASSEMBLY This invention relates to 'electrostatography,and

more particularly, to a novel transfer roller assembly for anelectrostatographic apparatus.

In the practice of electrostatography, as described in U.S. Pat. No.2,297,691 to Chester F. Carlson, an electrostatographic plate having asurface comprising a layer of photoconductive insulating materialaffixed to a conductive backing is used to support electrostatic images.In the usual method of carrying out the process, the plate iselectrostatically charged uniformly over its surface and then exposed toa light pattern of the image being reproduced to thereby discharge thecharge in the areas where light strikes the layer. The undischargedareas of the layer thus form an electrostatic charge pattern inconformity with the configuration of the original light pattern.

The latent electrostatic image may then be developed by contacting itwith a finely divided electrostatically attractable material, such as aresinous powder. The powder is held in the image areas by theelectrostatic fields on the layer. Where the field is greatest, the

greatest amount of material is deposited; and where the field is least,little or no material is deposited. Thus, a powder image is produced inconformity with the light image of the copy being reproduced. The powderis subsequently transferred to a sheet of paper or other surface andsuitably affixed to thereby form a permanent print.

The toner may be fixed by passing the sheet of paper or other surfaceincluding the transferred image between a heated roller and a secondroller in pressure contact therewith whereby the toner becomes fused tothe sheet of paper.

The image is generally transferred to an image receiving member bypassing sucha member between the photoconductive surface including thedeveloped image and a roller in contact therewith. In order to providequality copies during machine operation, there is need for continuousremoval of unwanted toner depositsupon the transfer roller.

An object of this invention is to provide a novel, unitized transferassembly.

Another object of this invention is to provide a novel transfer assemblyincluding a cleaning roller which may 7 be readily placed in operationalcontact with a transfer roller to be driven therewith and movable as aunit with the roller and drive means therefor.

These and other objects of the invention are obtained by providing atransfer assembly rotatably supported within thehousing of anelectrostatographic machine in juxtaposition to a photoconductivesurface therefor. The transfer assembly is provided with a transferroller, a rotary cleaning brush in brushing engagement with the surfaceof the roller. Both the brush and the roller I the accompanyingdrawings, wherein like numerals designate like parts throughout:

FIG. 1 is a schematic sectional view of an electrostatic reproductionmachine embodying the principles of the invention;

FIG. 2 is a view of one end of the transfer assembly showing the motionimparting means for the transfer roller;

FIG. 3 is an isometric view (greatly simplified) of the transfer rollerassembly;

FIG. 4 is a view of the other end of the assembly showing the motionimparting means for the rotary brush;

FIG. 5 is a rear view of the locking shaft assembly;

FIG. 6 is a side elevation view of a mounting frame for the transferroller assembly; and

FIG. 7 is a side view of the transfer roller assembly illustrating themovement thereof when disposed in juxtaposition to a photoconductivebelt of an electrostatographic machine.

For a general understanding of the illustrated copier/reproductionmachine in which the invention may be incorporated, reference is had toFIG. 1 in which the various system components for the machines areschematically illustrated.

A document D to be copied is placed upon a transparent support platen Pfixedly arranged in an illumination assembly, generally indicated by thereference numeral 10, positioned at the left end of the machine. Lightrays from an illumination system are flashed upon the document toproduce image rays corresponding to the informational areas. The imagerays are projected by means of an optical system onto the photosensitivesurface of a xerographic plate in the form of a flexible photoconductivebelt 12 arranged on a belt assembly, generally indicated by thereference numeral 14.

The belt 12 comprises a photoconductive layer of se lenium which is thelight receiving surface and imaging medium for the apparatus, on aconductive backing. The surface of the photoconductive belt is madephotosensitive by a previous step of uniformly charging the same bymeans of a corona generating device or corotron 13.

The belt is journaled for continuous movement upon three rollers 20, 21and 22 positioned with their axes in parallel. The photoconductive beltassembly 14 is 'slidably mounted upon two support shafts 23 and 24 withthe roller 22 rotatably supported on the shaft 23 which is-secured tothe frame of the apparatus and is rotatably driven by a suitable motorand drive assembly (not shown) in the direction of the arrow at aconstant rate. During exposure of the belt 12, the portion exposed isthat portion of the belt running between rollers 20 and 21. During suchmovement of the belt 12, the reflected light image of such originaldocument positioned on the platen is flashed on the surface of the beltto produce an electrostatic latent image thereon at exposure station A.

As the belt surface continues its movement, the electrostatic imagepasses through a developing station B in which there is positioned adeveloperassembly generally indicated by the reference numeral 15, andwhich provides development of the electrostatic image by means ofmultiple brushes 16 as the same moves through the development zone.

The developed electrostatic image is transported by the belt to atransfer station C wherein the presentinvention may be positioned andwhereat a sheet of copy paper is moved between a transfer roller and thebelt at a speed in synchronism with the moving belt in order toaccomplish transfer of the developed image solely by an electrical biason the transfer roller. There is providedat this station a sheettransport mechanism generally indicated at 17 adapted to transportsheets of paper from a paper handling mechanism generally indicated bythe reference numeral 18 to the developed image on the belt at thestation C.

After the sheet is stripped from the belt 12, it is con- Y veyed into afuser assembly, generally indicated by the reference numeral 19, whereinthe developed and transferred xerographic powder image on the sheetmaterial is permanently affixed thereto. After fusing, the

finished copy is discharged from the apparatus at a suitable point forcollection externally of the apparatus.

Further details regarding the structure of the belt assembly 14 andother machine processing components so far outlined are not necessary asthey form no part of the present invention.

Referring now to FIGS. 2, 3 and 4, there is illustrated retainingasemblies 76 in which is positioned one end pressure contact with thephotoconductive surface 12,

the handle 74 is moved clockwise from its full line position to itsdotted line position and locked against counterclockwise rotation in thelower notch 90a in the opening 90 of the receiving plate 86. Thisrotation causes rotation of the locking shaft 72. Such rotation atransfer assembly generally indicated as 30, having a I transfer roller32 secured to a shaft 34 which is mounted for rotation in suitablebearings supported in hub assemblies 36, 37. A pulley 38 is affixed toone end of the shaft 34 extending through the hub assembly 36 andengages an endless timing belt 40 entrained around an idler pulley 41and a drive pulley 42. The pulley 42 is secured to one end ofa driveshaft 44 which also supports the transfer assembly. The drive shaft 44is mounted for rotation in the hub assemblies 36, 37 above' the transferroller 32 in parallel with the shaft 34 and extends outwardly beyond thehub assemblies 36,

37. The other end of the drive shaft 44 beyond the hub assembly 37 issuitably connected to the main drive system for the machine. Bearings 48are positioned on the ends of the shaft 44 and are positioned. in framesupport assemblies, generally indicated as 50 and 52 (see FIGS. 5 and6).

Each of the frame support assemblies 50 and 52 is comprised of a framesection-54 having a cylindrically shaped machined surface56 forreceiving the bearings 48 of the support shaft 44. An upwardly extendingtab section 58 is formed on the frame section to receive a clamp 60pivotally mounted to the tab section 58, such as by a pin 62. The clamp60 is held in locking relationship to the frame section 54 by ascrew 64.By virtue of the bearings 48, one mounted-at each end of the shaft 44,the shaft supports the entire transfer assembly rocking movement uponthe machine frame. This shaft also serves to drive the transfer rollerand, as will be described, a rotary cleaning brush. The frame section 54is provided with a shaft receiving opening 66 and mounting holes 68 foraffixing the frame assembly 52 to the main body (not shown) of theelectrostato graphic machine. It is understood that the frame section 50is similarly formed with respect to frame section v of the locking shaftcauses the lever elements to rotate clockwise about the shaft 72 forcingthe pin section 82 thereof to press against one side of the cooperatinggrooves 84 on the hub assemblies thereby causing slight rocking movementor rotation of the entire transfer assembly about the shaft 44. This, inturn, forces under spring tension the transfer roller assembly 30against the photoconductive surface 12. This relationship of pressurecontact of the transfer roller 32 with the photoconductive member 12,facilitates image transfer and permits the transfer roller 32 andphotoconductive member 12 to function as part of the transport systemfor image receiving members. Shifting of the handle 74 from the lockingposition back to its full line position wherein the handle is in theupper notch b of the opening 90 releases the forces that the pins 82have upon the side-of the grooves 84 causing counterclockwise rocking orrotation of the transfer assembly 30 on its supporting shaft 44. Thisrocking movement allows the assembly to move away from thephotoconductive surface thereby facilitating the correction of paperjams and to permit removal of the photoconductive members from themachine.

Also mounted for rotation within the transfer assembly, as a movablepart therewith is a cleaning brush having stub shafts 102, one at eachend thereof, extending into the hub assemblies 36, 37. The hub assembly37, as shown in FIG. 4, includes the drive train for effecting rotationof the brush 100'in accordance with the transfer roller 32. Asemi-cylindricalcovering or housing 104 for containing the brush issuitably mounted in the hub assemblies 36, 37. The bristles of the brushare in interferring engagement with the surface of the roller 32 andupon relative rotation between the roller and the rotary brush, asweeping action is accomplished. This sweeping action flicks into thehousing 104, the loose toner particles which'deposit upon the texturedsurface of the transfer roller and which may adhere to the back ornon-transfer side of sheets of paper. The brushed away toner particlesmay adhere mechanically or electrostatically to the roller surface andif left unattended would accumulate and in time cause serious qualitydefects of the copies made by the machine. The housing 104 is connectedby way of a vacuum duct 106 to a vacuum source in the machine The drivetrain for producing rotation of the rotary brush 100 includes a drivegear 108 mounted on the drive shaft 44 to be driven thereby. The gear108 is in mesh with an idler gear 110 which, in turn, is in mesh with agear 112 secured to the adjacent stub shaft 102 for the rotary brush100. With this gear arrangement, the transfer roller 32 and the brush100 rotate in the same direction during brushing operation givingmaximum difference in relative surface velocity. The relationship of thediameters of the gears 108, 110 and 112 is such as to provide anapproximate ratio of :1 to the rotary speed relationship of the cleaningbrush to the transfer roller, which ratio has been found to be optimumin cleaning efficiency. This provides an impact velocity for the brushbristles relative to the toner particles which is of sufficient force todislodge the particles dependently of the rotation imparted to therotary cleaning brush. Other modifications of the present invention willoccur to those skilled in the art upon a reading of the presentdisclosure which modifications are intended to be included within thescope of this invention.

What is claimed is:

1. In an electrostatographic machine having a movable photoconductivemember:

a transfer assembly having a transfer roller mounted proximate to saidphotoconductive member, a rotary cleaning brush mounted adjacent saidroller and having bristles in interferring engagement with the surfaceof said roller, said roller and said brush being mounted to rotate inthe same direction, and means for pivotally supporting said assembly sothat said roller can be moved into and out of contact with saidphotoconductive member, said pivotally supporting means permitting saidroller and said brush to be moved as a unit.

2. The combination set forth in claim 1, wherein the ratio of the speedof rotation of said brush relative to that of said transfer roller isapproximately 10:1.

1. In an electrostatographic machine having a movable photoconductivemember: a transfer assembly having a transfer roller mounted proximateto said photoconductive member, a rotary cleaning brush mounted adjacentsaid roller and having bristles in interferring engagement with thesurface of said roller, said roller and said brush being mounted torotate in the same direction, and means for pivotally supporting saidassembly so that said roller can be moved into and out of contact withsaid photoconductive member, said pivotally supporting means permittingsaid roller and said brush to be moved as a unit.
 2. The combination setforth in claim 1, wherein the ratio of the speed of rotation of saidbrush relative to that of said transfer roller is approximately 10:1.